Publications by authors named "Nanwintoum S Bimbile Somda"

Article Synopsis
  • - The sterile insect technique involves releasing sterile male insects to mate with wild females, effectively reducing the population by inducing sterility in females and is being developed for Aedes mosquitoes.
  • - High ratios of sterile males to wild females can lead to decreased longevity and feeding success in female Aedes mosquitoes due to mating harassment and reduced blood uptake.
  • - A field trial in China showed an 80% reduction in female biting rates and a 40% decrease in female mosquito density, indicating this technique can also lower disease transmission by increasing female mortality and reducing contact with hosts.
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Genetic sexing strains (GSS), such as the Ceratitis capitata (medfly) VIENNA 8 strain, facilitate male-only releases and improve the efficiency and cost-effectiveness of sterile insect technique (SIT) applications. Laboratory domestication may reduce their genetic diversity and mating behaviour and hence, refreshment with wild genetic material is frequently needed. As wild males do not carry the T(Y;A) translocation, and wild females do not easily conform to artificial oviposition, the genetic refreshment of this GSS is a challenging and time-consuming process.

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Article Synopsis
  • - The study focuses on developing a new method for safely transporting sterile male mosquitoes over long distances for pilot programs using the sterile insect technique (SIT).
  • - Different types of mosquito transport boxes were tested to evaluate how well the mosquitoes survived, flew, and sustained any physical damage during transit, aiming for high-quality delivery from the lab to field sites.
  • - The results showed that the new transport method allows for successful shipment of sterile males for up to four days, achieving over 90% survival after 48 hours and improving their escape ability by over 20% with a recovery period post-transport.
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The sterile insect technique (SIT) is based on the inundatory field release of a target pest following their reproductive sterilization via exposure to radiation. Until recently, gamma irradiation from isotopic sources has been the most widely used in SIT programs. As isotopic sources are becoming increasingly expensive, especially for small programs, and regulations surrounding their procurement and shipment increasingly strict, irradiation capacity is one of the limiting factors in smaller or newly developing SIT projects.

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Article Synopsis
  • The study examines how the developmental stage of mosquitoes influences their reaction to ionizing radiation, focusing on adult males and the challenge of effective irradiation without compromising quality.
  • It compares the effects of irradiating mosquitoes in nitrogen (N), in air after nitrogen treatment (PreN), and in air, revealing that higher doses of radiation lead to lower egg hatch rates, particularly in nitrogen environments.
  • The findings suggest that nitrogen treatments can enhance the longevity of irradiated males and are effective for immobilization, with PreN emerging as the most efficient method for achieving sterility with minimal impact on male quality and shorter immobilization times.
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Background: South Africa has set a mandate to eliminate local malaria transmission by 2023. In pursuit of this objective a Sterile Insect Technique programme targeting the main vector Anopheles arabiensis is currently under development. Significant progress has been made towards operationalizing the technology.

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Article Synopsis
  • The study focuses on enhancing the sterile insect technique (SIT) by standardizing the quality control flight test device (FTD) to ensure a reliable release of high-quality sterile male mosquitoes.
  • Key factors that affect mosquito escape rates were identified as tube color, the use of lures and fans, mosquito species, age, and density, while factors like test duration and fan speed were found to be less significant.
  • A new, more affordable version of the FTD (version 2.0) was developed and successfully tested, proving effective for evaluating mosquito flight ability for SIT and similar programs.
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Reproductive sterility is the basis of the sterile insect technique (SIT) and essential for its success in the field. Numerous factors that influence dose-response in insects have been identified. However, historically the radiation dose administered has been considered a constant.

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Article Synopsis
  • The sterile insect technique is a sustainable approach for mosquito control, involving the release of sterile males into the wild.
  • The study explored how different mantis and gecko species prey on various mosquito species while considering the impact of specific treatments like chilling, marking, and irradiation on predation rates.
  • Results indicated that predation was consistent across treatments, with minimal effect on predation risk unless mosquitoes were exposed to excessive irradiation; suggesting further standardized trials could enhance quality control for the method.
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  • The study examines how water quality, specifically hardness and electrical conductivity, affects the life cycle of mosquitoes, focusing on their development and productivity in different water types.
  • It compares the responses of two species of mosquitoes to various water mixtures, including purified water and tap water with varying hardness and conductivity levels.
  • Results show that higher water hardness and conductivity lead to longer pupation times, reduced productivity, and larger female sizes in one species, indicating that water with hardness over 140 mg/l CaCO3 or conductivity above 368 µS/cm is not suitable for optimal mosquito rearing.
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Article Synopsis
  • * The new MRC produced over a million eggs with minimal loss and demonstrated good measures for tracking adult survival rates.
  • * Results indicate that the new MRC is effective for mass-rearing in SIT programs, although further adjustments are needed to reduce egg collection escape issues. *
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Article Synopsis
  • The Sterile Insect Technique uses radiation-induced sterile males to control pest populations, and effective irradiation protocols are necessary for high-quality sterile insects.
  • A study was conducted on Aedes aegypti, Ae. albopictus, and Anopheles arabiensis to evaluate their oxygen consumption in water and examine the effects of radiation in hypoxic versus normoxic conditions.
  • Results showed that all species quickly depleted dissolved oxygen in water, with An. arabiensis being the fastest, and that hypoxic conditions provided a protective effect during irradiation, notably more significant in An. arabiensis.
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Article Synopsis
  • Resistance to insecticides for controlling Aedes mosquitoes is increasing, making traditional methods ineffective, and highlighting the need for alternative techniques like the Sterile Insect Technique (SIT).
  • A prototype low-cost plexiglass mass-rearing cage was developed to improve the egg production and hatch rates when compared to existing stainless-steel options, alongside an adult-index to estimate mosquito survival rates.
  • The prototype cage outperformed the stainless-steel cage in egg production and hatch rates, is more affordable, easy to handle, and supports more efficient mosquito rearing.
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Article Synopsis
  • The increase in mosquito mass production is driven by techniques like sterile insect technique (SIT) and a need for cost-effective rearing ingredients.
  • A study tested two black soldier fly (BSF) powder-based diets to replace the expensive bovine liver powder (BLP) used in larval diets for Aedes aegypti and Ae. albopictus mosquitoes.
  • Results showed that BSF powder did not harm mosquito development and could improve certain qualities, making it a viable replacement for BLP, particularly when paired with brewer's yeast for A. albopictus.
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Background: The sterile insect technique (SIT) for use against mosquitoes consists of several steps including the production of the target species in large numbers, the separation of males and females, the sterilization of the males, and the packing, transport and release of the sterile males at the target site. The sterility of the males is the basis of the technique; for this, efficient and standardized irradiation methods are needed to ensure that the required level of sterility is reliably and reproducibly achieved. While several reports have found that certain biological factors, handling methods and varying irradiation procedures can alter the level of induced sterility in insects, few studies exist in which the methodologies are adequately described and discussed for the reproductive sterilization of mosquitoes.

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Article Synopsis
  • The black soldier fly, yellow mealworm, and house fly are effective protein sources for rearing mosquito larvae due to their easy breeding and beneficial environmental and nutritional qualities.
  • A new diet based on insect meal offers a more cost-effective alternative to traditional animal-based diets for producing Aedes albopictus and Ae. aegypti mosquitoes.
  • Two recommended mixtures for optimal mosquito production consist of combinations of tuna meal, black soldier fly, and brewer’s yeast, which could also be applicable to other mosquito species for genetic control efforts.
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Article Synopsis
  • Swarming is crucial for the reproduction of Anopheles arabiensis mosquitoes, and understanding their behavior and environmental factors can help improve control strategies.
  • The study found that swarming occurs year-round, with variations in start and end times based on sunset and seasonal rainfall, and that mating activity peaks during the dry season.
  • Interventions targeting swarms and utilizing sterile males during the rainy season could enhance efforts to reduce mosquito populations and the spread of malaria.
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Insect mass-rearing is an essential requirement for the sterile insect technique. Production at a large scale requires the development of standardized rearing procedures to produce good quality males able to compete with wild males to mate with wild females. Three sets of experiments (using trays placed on the table, the whole tray-rack system, and climate-controlled chambers) have been conducted aiming to determine the optimal water temperature and number of eggs to aliquot into each larval rearing tray to achieve the highest production of pupae.

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Background: Larval nutrition, particularly diet quality, is a key driver in providing sufficient numbers of high quality mosquitoes for biological control strategies such as the sterile insect technique. The diet currently available to mass rear Anopheles arabiensis, referred here to as the "IAEA diet", is facing high costs and difficulties concerning the availability of the bovine liver powder component. To promote more affordable and sustainable mosquito production, the present study aimed to find alternative diet mixtures.

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Background: Anopheles arabiensis is one of the major malaria vectors that put millions of people in endemic countries at risk. Mass-rearing of this mosquito is crucial for strategies that use sterile insect technique to suppress vector populations. The sterile insect technique (SIT) package for this mosquito species is being developed by the Insect Pest Control Subprogramme of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture.

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